/Engine/Plugins/2D/Paper2D/Source/Paper2D/Classes/PaperFlipbook.h
Returns the sprite at the specified keyframe index, or nullptr if none exists.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category="Sprite") UPaperSprite * GetSpriteAtFrame ( int32 FrameIndex ) const